We have previously shown that the density of capillary supply in skeletal muscle of man correlates with insulin resistance. We postulated that since the unfenestrated capillaries of muscle are relatively impermeable to insulin then the increased insulin resistance in those with low capillary density might be due to altered kinetics of insulin penetration to its sites of action in muscle. To test this hypothesis further we have developed a method of directly collecting lymph from a peripheral lymphatic. The method allows the collection of 0.7 to 3.7 ml/hour of lymph which is sufficient for analysis for glucose, insulin, and labeled inulin. Preliminary results have shown that insulin concentrations in lymph rise very slowly after plasma insulin levels are raised and by 2-1/2 hours are still only about 30% of arterial concentrations.